B.S.M. KUMAR, P.M. BASHA#
Department of Zoology, Jnanabharathi Campus, Bangalore University, Bangalore 560 056, India
The mitochondrion is the focal point of bioenergetic interactions that manage various cell functions like Ca2+ flux management, programmed cell death, reactive oxygen species (ROS) generation, and energy dynamics involving ATP generation and dissemination to the cell. The current study conducted to understand the role of Ca2+ in varying mitochondrial membrane potentials in alleviating the oxidative burden on the cell. Brain mitochondria, isolated from rats aged 2-3 weeks (neonatal), 2-3 months (young adult), and 2-3 years (aged) of age, were used in the study. Mitochondria isolated from aged rats displayed elevated ROS production levels upon Ca2+ treatment, measured as a function of DCF fluorescence intensity. Rhodamine-123 fluorescence measured the alterations in mitochondrial membrane potential, indicating a significant depolarization in the mitochondria isolated from aged rats as compared to mitochondria isolated from the other age groups. Experiments with ruthenium red, an effective blocker of Ca2+ uniporter, confirms the Ca2+-dependent membrane depolarization and ROS generation. Large mitochondrial membrane potential dissipation observed in the aged rats explains the vulnerability of the same to oxidative stress during aging.
Key words: Calcium, membrane potential, reactive oxygen species, aging, mitochondria.
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